// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
#define EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H

#if EIGEN_HAS_VARIADIC_TEMPLATES

#include <initializer_list>

namespace Eigen {

/** \class TensorInitializer
  * \ingroup CXX11_Tensor_Module
  *
  * \brief Helper template to initialize Tensors from std::initializer_lists.
  */
namespace internal {

    template <typename Derived, int N> struct Initializer
    {
        typedef std::initializer_list<typename Initializer<Derived, N - 1>::InitList> InitList;

        static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
                        Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
                        const InitList& vals)
        {
            int i = 0;
            for (const auto& v : vals)
            {
                (*indices)[traits<Derived>::NumDimensions - N] = i++;
                Initializer<Derived, N - 1>::run(tensor, indices, v);
            }
        }
    };

    template <typename Derived> struct Initializer<Derived, 1>
    {
        typedef std::initializer_list<typename traits<Derived>::Scalar> InitList;

        static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
                        Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
                        const InitList& vals)
        {
            int i = 0;
            // There is likely a faster way to do that than iterating.
            for (const auto& v : vals)
            {
                (*indices)[traits<Derived>::NumDimensions - 1] = i++;
                tensor.coeffRef(*indices) = v;
            }
        }
    };

    template <typename Derived> struct Initializer<Derived, 0>
    {
        typedef typename traits<Derived>::Scalar InitList;

        static void
        run(TensorEvaluator<Derived, DefaultDevice>& tensor, Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>*, const InitList& v)
        {
            tensor.coeffRef(0) = v;
        }
    };

    template <typename Derived, int N>
    void initialize_tensor(TensorEvaluator<Derived, DefaultDevice>& tensor, const typename Initializer<Derived, traits<Derived>::NumDimensions>::InitList& vals)
    {
        Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions> indices;
        Initializer<Derived, traits<Derived>::NumDimensions>::run(tensor, &indices, vals);
    }

}  // namespace internal
}  // namespace Eigen

#endif  // EIGEN_HAS_VARIADIC_TEMPLATES

#endif  // EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
